1. Field of the Invention
The present invention relates to a fuel tank opening and closing device for opening a flap valve using the insertion force of a fueling nozzle to fuel a fuel tank.
2. Description of the Related Art
An example of a fuel tank opening and closing device is disclosed in JP-A 2007-331518 as a fuel cap including a flap valve mechanism. The flap valve mechanism is equipped with an opening and closing member arranged at the inlet of the fuel path, and the shaft protruding from the end part of the opening and closing member, the shaft is inserted into the through hole of the tank opening forming member and supported to be rotatable. The opening and closing member is sealed by energization of the spring in the closing direction. With this constitution, the inlet is opened by the opening and closing member being pressed with the fueling nozzle during fueling in opposition to the energization force of the spring, and fuel is injected from the fueling nozzle.
However, when the tank opening forming member is formed from resin, due to shrinkage of the resin, the through hole does not become a cross sectional circle that matches the shaft of the opening and closing member, positional displacement of the shaft occurs in assembly. The positional displacement causes to be fluctuation of the seal surface pressure of the opening and closing member. Because of this, there was the problem that a great deal of effort was required to increase the through hole forming precision.